Some wood frogs spend winter doing something that sounds like a failed magic trick: they freeze, stop breathing, stop pumping blood, and then come back when the weather warms up.

As temperatures drop, ice can form in parts of the frog’s body. Its heart may stop beating, and it can appear lifeless. But the frog is not simply “frozen solid” like an ice cube. Its body floods key tissues with natural antifreeze-like chemicals, including glucose and urea, which help protect cells from deadly damage.

The trick is where the ice forms. Ice can build up outside the cells, while the cells themselves are defended from bursting or drying out too severely. When spring arrives, the frog thaws from the inside out, its heart starts again, and it eventually hops away as if it did not just spend months as a living popsicle.

Nature didn’t invent cryonics in a lab; it hid it under dead leaves.